Didn't Qantas do the numbers long and hard on B772LR PER-LHR direct and decide it didn't work. And one would assume, that was with a much higher proportion of premium customers (hence higher yields) than V Aus would be carrying.
Good on them for giving it a shot, but if Bruce the Bogan is willing to fly on Asiana via Seoul (for example) with an overnight on the way in order to get the cheapest possible fare to Europe, then that's what they'll do. V Australia will need to charge a premium to make the service work and their target market might probably won't like it.